This application relates generally to mechanical circulatory support systems, and more specifically relates to improved rotor designs in axial flow blood pumps.
Ventricular assist devices, known as VADs, are implantable blood pumps used for both short-term (i.e., days, months) and long-term applications (i.e., years or a lifetime) where a patient's heart is incapable of providing adequate circulation, commonly referred to as heart failure or congestive heart failure. According to the American Heart Association, more than five million Americans are living with heart failure, with about 670,000 new cases diagnosed every year. People with heart failure often have shortness of breath and fatigue. Years of living with blocked arteries or high blood pressure can leave your heart too weak to pump enough blood to your body. As symptoms worsen, advanced heart failure develops.
A patient suffering from heart failure, also called congestive heart failure, may use a VAD while awaiting a heart transplant or as a long term destination therapy. In another example, a patient may use a VAD while recovering from heart surgery. Thus, a VAD can supplement a weak heart (i.e., partial support) or can effectively replace the natural heart's function. VADs can be implanted in the patient's body and powered by an electrical power source inside or outside the patient's body.
While blood pumps have been effective for many patients, because patients using such devices are living longer, further improvements that prolong the effectiveness and lifetime of such blood pump devices are desired. One challenge frequently encountered in axial blood pumps is that performance of the rotor, the bearing assembly or associated seal can degrade over time. Thus, there is a need for the ability to monitor and assess the performance of the pump over the lifetime of the device.
There are various conventional methodologies used for characterizing the normal operating conditions, wear, and the life of mechanical rotating assemblies. Some conventional techniques include vibration analysis, oil analysis, and ultrasound techniques. Since blood pumps are implanted devices, servicing the blood pump is not feasible. Further, commonly used conventional types of analysis used to monitor rotating machinery are not possible (e.g., oil analysis or attaching devices externally to characterize vibration). Thus, there is a need for improved blood pump designs that allow for monitoring of bearing performance and seal performance over the lifetime of the device in a non-invasive manner.